Relationship between physical activity and hip pain in persons with and without cam or pincer morphology: a population-based case-control study.

OBJECTIVES: The purpose of the study was to determine if physical activity (PA) is a risk factor for persistent or recurrent hip pain in young and middle-aged persons with and without radiographic findings of cam or pincer morphology (CPM). METHODS: A population sample of persons aged 20-49 with (cases) and without (controls) hip pain in Metro Vancouver, Canada, was selected through random digit dialing (RDD). Self-reported PA was expressed as average energy expenditure (MET-hours) per year, over lifetime. CPM was defined as alpha angle >55°, lateral centre edge angle (LCE) >40°, or positive cross-over sign. RESULTS: Data were obtained for 500 subjects, 269 cases and 231 controls. Prevalence of radiographic CPM was 49% in the cases and 44% in the controls. In a logistic regression model adjusted for age, gender and CPM, total lifetime PA, including occupational, domestic and recreational activities, was significantly associated with hip pain (Odds ratio (OR) 1.30 per 1000 MET-hours, 95% CI 1.15-1.38). The effect of total PA was observed in those with CPM (1.44, 1.17-1.78) and without CPM (1.23, 1.04-1.45). For domestic activities, the association was seen only in those with CPM (significant interaction). When PA was categorized into quartiles, higher levels of PA were associated with a greater risk of pain. CONCLUSIONS: PA, as measured by average energy expenditure over lifetime is a risk factor for hip pain in young and middle-aged persons. For some activities, the risk is likely increased in persons with radiographic evidence of CPM.

The validity of a non-radiologist reader in identifying cam and pincer femoroacetabular impingement (FAI) using plain radiography.

The purpose of this study was to evaluate the validity and reliability of a radiographic diagnosis of femoroacetabular impingement (FAI) by a non-radiologist. Symptomatic FAI is prevalent and thought to be a cause of hip osteoarthritis. However, the diagnosis is often delayed by 1-2 years, in large part because radiographic findings are often subtle and clinicians have been unaware of their significance. The purpose of this study was to evaluate the validity of a radiographic diagnosis of FAI by a non-radiologist. A population-based sample of 701 subjects was recruited in Vancouver, Canada. For the current study, 50 subjects were selected-40 randomly from the population sample and 10 from an orthopedic practice with confirmed FAI. An anterior-posterior pelvis and bilateral Dunn radiographs were acquired and read by a fellowship-trained musculoskeletal radiologist and a third-year medical student who received basic training in radiographic signs of FAI. Three radiographic signs were evaluated: the lateral center edge angle, alpha angle and crossover sign. Validity was assessed using sensitivity and specificity, Bland-Altman limits of agreement and kappa. The sample contained 65% women (n = 31), was 62% Caucasian and 38% Chinese and had a mean age of 38.3 years. For correctly diagnosing FAI, the non-radiologist reader had a sensitivity of 0.83 and specificity of 0.87. Intra-rater κ value was 0.72, and prevalence-adjusted bias-adjusted κ was 0.76. This study provides evidence that a non-radiologist can accurately and reliably identify FAI on plain films.

Patient-reported outcomes in women with gestational diabetes: a longitudinal study.

BACKGROUND: Gestational Diabetes Mellitus (GDM) is a common health problem among pregnant women and may be associated with distress. PURPOSE: The purpose of the study was to describe changes in patient-reported outcomes in women with GDM and identify factors associated with increased distress in these patients. RESEARCH DESIGN: The study was conducted in 205 women diagnosed with GDM. Study participants underwent a physical examination and completed a questionnaire two times during pregnancy. On average, the questionnaire was completed at 27 weeks of gestation at baseline and 36 weeks at follow-up. The questionnaire included socio-demographic and clinical variables, standardized patient-reported outcome measures, and questions about the impact of GDM on daily life, satisfaction with care, knowledge about GDM, and social and professional support. Our main outcome of interest was diabetes-related distress, measured by the Problem Areas in Diabetes (PAID) questionnaire. Data were analyzed using descriptive statistics and multivariable regression models. RESULTS: At baseline, 80% of the women were satisfied with their diabetes care and 58% said they managed their diabetes well. The proportion reporting little or no knowledge of GDM dropped from almost 50% at baseline to 14% at follow-up. However, the proportion reporting that GDM affected their social life increased from 26 to 35%, and the proportion reporting interference with family life increased from 14 to 26%. Insulin treatment, frequency of blood glucose measurements, lack of knowledge about GDM, and lack of support from family and health care providers were strongly and significantly associated with distress. CONCLUSION: In women with GDM, intensified treatment and lack of informational and social support are associated with distress. These aspects of GDM care appear to be appropriate targets for future research and interventions aimed at reducing the level of distress in these patients.

The relationship between subchondral sclerosis detected with MRI and cartilage loss in a cohort of subjects with knee pain: the knee osteoarthritis progression (KOAP) study.

PURPOSE: To assess the association between subchondral sclerosis detected at baseline with MRI and cartilage loss over time in the same region of the knee in a cohort of subjects with knee pain. METHODS: 163 subjects with knee pain participated in a longitudinal study to assess knee osteoarthritis progression (KOAP). Subjects received baseline knee radiographs as well as baseline and 3-year follow-up MRI examinations. Baseline subchondral sclerosis and bone marrow lesions (BMLs) were scored semiquantitatively on MRI in each region from 0 to 3. Cartilage morphology at baseline and follow-up was scored semiquantitatively from 0 to 4. The association between baseline subchondral sclerosis and cartilage loss in the same region of the knee was evaluated using logistic regression, adjusting the results for age, gender, body mass index, and the presence of concomitant BMLs. RESULTS: The prevalence of subchondral sclerosis detected by MRI in the regions of the knee varied between 1.6% (trochlea) and 17% (medial tibia). The occurrence of cartilage loss over time in regions varied between 6% (lateral tibia) and 13.1% (medial femur). The prevalence of radiographically-detected subchondral sclerosis in compartments varied from 2.9% (patellofemoral) to 14.2% (medial tibiofemoral). In logistic regression models, there were no significant associations between baseline subchondral sclerosis detected by MRI and cartilage loss in the same region of the knee. CONCLUSION: Baseline subchondral sclerosis as detected by MRI did not increase the risk of cartilage loss over time.

The association of magnetic resonance imaging (MRI)-detected structural pathology of the knee with crepitus in a population-based cohort with knee pain: the MoDEKO study.

Osteoarthritis (OA) is the most common arthropathy of the knee joint(1). Symptoms reported by patients and signs noted during physical examination guide clinicians in identifying subjects with knee OA(2-4). Pain is one of the most important symptoms reported by subjects with knee OA(2,3). Although very common, pain is a non-specific symptom, related to pathology in several structures within the knee joint, and includes synovitis(5), subchondral bone marrow lesions(6), and joint effusion(7). Further, pain is a subjective symptom that cannot be directly measured or assessed during physical examination. Crepitus or crepitation in association with arthritis is defined as a crackling or grinding sound on joint movement with a sensation in the joint. Crepitus may occur with or without pain and is a common finding during physical examination in subjects with knee OA(2-4,8,9). It is not known whether crepitus is related to pathology in various structures within the knee. The aim of our study was to determine the cross-sectional associations of structural pathologies within the knee with crepitus in a population-based cohort with knee pain, using magnetic resonance imaging (MRI). Subjects with knee pain were recruited as a random population sample, with crepitus assessed in each compartment of the knee using a validated and standardized approach during physical examination(10). MRI of the knee was performed to assess cartilage morphology, meniscal morphology, osteophytes, cruciate ligaments, and collateral ligaments. For both compartment-specific and whole-knee analyses, a multiple logistic regression analysis was performed to assess the associations of MRI-detected structural pathology with crepitus, adjusting for potential confounders. Variables were selected by backwards elimination within each compartment and in the overall knee models, and only statistically significant variables remained in the "selected" models; remaining variables in these models are adjusted for each other. An increased risk for compartment-specific crepitus was associated with osteophytes at the patellofemoral (PF) and lateral tibiofemoral (LTF) joints. Crepitus was associated with osteophytes and medial collateral ligament (MCL) pathology at the medial tibiofemoral (MTF) compartment, but cartilage damage was negatively associated with crepitus at this compartment. In the selected whole-knee model, only meniscal tears were associated with an increased risk for general crepitus. Thus, it seems that crepitus may be associated with pathology in several internal structures.

Natural history of cartilage damage and osteoarthritis progression on magnetic resonance imaging in a population-based cohort with knee pain.

OBJECTIVES: To determine the natural history of cartilage damage and of osteoarthritis (OA) progression using magnetic resonance imaging (MRI); to evaluate whether OA progression varies by stage of disease. METHODS: A population-based cohort with knee pain was assessed clinically, with X-ray (Kellgren-Lawrence [KL] grading) and MRI. Cartilage was graded 0-3 on six joint surfaces. Frequency of cartilage damage change was determined for each joint site. Progression of OA was defined as a worsening of MRI cartilage damage by ≥1 grade in at least two joint sites or ≥2 grades in at least one joint site. The association of KL grade with OA progression was evaluated using parametric lifetime regression analysis. RESULTS: 163 subjects were assessed at baseline and follow-up (mean 3.2 years). KL grade ≥2 was present in 39.4% at baseline. An increase in cartilage damage by ≥1 grade was seen in 8.0-14.1% of subjects at different joint sites. OA progression on MRI was present in 15.5%. Baseline KL grade was a significant predictor of OA progression with hazard ratio (HR) of 6.5 (95% confidence interval [CI] 1.4-30.7), 6.1 (95% CI 1.3-28.9), and 9.2 (95% CI 1.9-44.9) for KL grades 1, 2 and ≥3, respectively. CONCLUSION: A low OA progression rate was seen over 3 years in this population-based symptomatic cohort. Radiographic severity, including KL grade 1, was a significant predictor of OA progression. Future interventions aimed at reducing progression will need to target not only radiographic OA, but also those with early abnormalities suggestive of pre-radiographic OA.

Influence of lifetime hip joint force on the risk of self-reported hip osteoarthritis: a community-based cohort study.

OBJECTIVE: To investigate the influence of cumulative lifetime hip joint force on the risk of self-reported medically-diagnosed hip osteoarthritis (OA). DESIGN: Prospective cohort. SETTING: General population. PARTICIPANTS: Members of Canadian Association of Retired Persons, community-dwelling. MAIN OUTCOME: Health-professional diagnosed hip OA, self-reported. METHODS: Exposure data on lifetime physical activity type (occupational, household, sport) and dose (frequency, intensity, duration) was collected in 2005. Subjects were ranked in terms of a 'cumulative peak force index' (CFPI), a measure of lifetime mechanical hip joint force. Multivariable survival analyses were performed to obtain adjusted effects for mean lifetime exposure and during 5-year age periods. RESULTS: Of 2918 subjects aged 45-85, 176 (6.03%) developed hip OA during the 2-year follow up (43 men, 133 women). The highest quintile of mean lifetime hip CPFI (HR 2.32; 95% CI 1.31-4.12), and high hip force in three age periods (35-39, 40-44, 45-49) were independently associated with hip OA. Previous hip injury was an approximate five-fold risk for development of hip OA across all models. In analysis by activity domain (occupation, sport, household), there was a trend (non-significant) for the highest quintile of occupational force, but not sport or household, to be associated with hip OA. CONCLUSIONS: A newly proposed measure of lifetime mechanical hip force was used to estimate the risk of self-reported, medically-diagnosed hip OA. While there are important limitations, this prospective study suggests that lifelong physical activity is generally safe. Very high levels of lifetime force from all domains combined, and in particular from occupational forces, may be important in the etiology of hip OA.

Development of a population-based microsimulation model of osteoarthritis in Canada.

OBJECTIVES: The purpose of the study was to develop a population-based simulation model of osteoarthritis (OA) in Canada that can be used to quantify the future health and economic burden of OA under a range of scenarios for changes in the OA risk factors and treatments. In this article we describe the overall structure of the model, sources of data, derivation of key input parameters for the epidemiological component of the model, and preliminary validation studies. DESIGN: We used the Population Health Model (POHEM) platform to develop a stochastic continuous-time microsimulation model of physician-diagnosed OA. Incidence rates were calibrated to agree with administrative data for the province of British Columbia, Canada. The effect of obesity on OA incidence and the impact of OA on health-related quality of life (HRQL) were modeled using Canadian national surveys. RESULTS: Incidence rates of OA in the model increase approximately linearly with age in both sexes between the ages of 50 and 80 and plateau in the very old. In those aged 50+, the rates are substantially higher in women. At baseline, the prevalence of OA is 11.5%, 13.6% in women and 9.3% in men. The OA hazard ratios for obesity are 2.0 in women and 1.7 in men. The effect of OA diagnosis on HRQL, as measured by the Health Utilities Index Mark 3 (HUI3), is to reduce it by 0.10 in women and 0.14 in men. CONCLUSIONS: We describe the development of the first population-based microsimulation model of OA. Strengths of this model include the use of large population databases to derive the key parameters and the application of modern microsimulation technology. Limitations of the model reflect the limitations of administrative and survey data and gaps in the epidemiological and HRQL literature.

Measuring the health burden of chronic disease and injury using health adjusted life expectancy and the Health Utilities Index.

OBJECTIVES: To estimate the burden of illness from chronic disease and injury using a population based health survey, which contains both measures of chronic disease and a utility based health related quality of life (HRQOL) measure. DESIGN: An adapted Sullivan method was used to calculate cause deleted health adjusted life expectancies for chronic conditions. SETTING: Ontario, Canada, 1996/97. SUBJECTS: The 1996/97 Ontario Health Survey (n=35 527) was used to estimate the prevalence of chronic conditions. A cause deleted approach was used to estimate the impact of these conditions on the Health Utilities Index (HUI). Cause deleted probabilities of dying were derived with the cause eliminated life table technique and death data from vital statistics for Ontario 1996/97 (n=156 610). RESULTS: Eliminating cardiovascular disease and cancer will cause an "expansion of morbidity", while eliminating mental conditions and musculosketal disorders will result in a "contraction of morbidity". The HUI score varies depending on chronic condition, age, and sex-most of which were assumed not to vary in previous summary measures of population health. CONCLUSIONS: Health adjusted life expectancy estimated for chronic conditions using a utility based measure of health related quality of life from population health surveys addresses several limitations of previous studies that estimate the burden of disease using either a categorical measure of disability or expert opinion and related epidemiological evidence.

Cross-cultural comparisons of health status in Canada using the Health Utilities Index.

OBJECTIVE: The purpose of this study was to examine the differences in health status, as measured by the Health Utilities Index (HUI), among seven cultural groups in Canada defined by place of birth and language. DESIGN: The study analysed cross-sectional data from the National Population Health Survey conducted by Statistics Canada in 1994-95. RESULTS: Age-standardized prevalence of dysfunction, defined as HUI < 0.83, varied from 12.7% in English-speaking immigrants to 17.8% in French-speaking Canadians. Considerable differences between the groups were found in the reporting of pain, emotional function, and cognitive function. The variation in HUI scores across the cultural groups could not be explained by differences in socioeconomic status and self-reported chronic conditions. CONCLUSIONS: Although the healthy immigrant effect is probably responsible for some of the variation in health status among cultural groups in Canada, considerable differences exist within the immigrant and Canadian-born populations. Cultural factors may have a substantial effect on the reporting of pain and mental health problems. Further studies are needed to determine the cross-cultural validity of the HUI.

Can the health utilities index measure change?

BACKGROUND: The Health Utilities Index (HUI) is a multidimensional, preference-weighted measure of health status. It comprises eight health attributes, aggregated into a single utility score. OBJECTIVES: The purpose of the study was to investigate the ability of the HUI to detect changes in health status in a general population cohort. RESEARCH DESIGN: Health status changes were analyzed in the full cohort and in persons who were diagnosed with chronic conditions, hospitalized, or became restricted in daily activities. SUBJECTS: To assess responsiveness, longitudinal data was used from the National Population Health Survey conducted in Canada in 1994 - 1995 and 1996 - 1997. We used cross-sectional data from the 1996 sample to classify chronic conditions into mild, moderate, and severe. MEASURES: Two measures of responsiveness were calculated: Standardized Response Mean (SRM) and Sensitivity Coefficient (SC). The HUI was compared with a global health index-the Self-Rated Health (SRH) scale. RESULTS: HUI scores improved between the two NPHS cycles in all age-sex groups, except men 65 years of age and older. Among the respondents who remained free of chronic conditions, improvements were seen primarily in the cognitive and emotional domains. The HUI deteriorated among persons who were diagnosed between the two cycles with a severe chronic condition, were hospitalized, or became restricted in activity, but not in those diagnosed with a moderate condition. The SRMs were generally smaller for the HUI compared with the SRH. CONCLUSIONS: The HUI responds to changes in health status associated with serious chronic illnesses. However, changes in the HUI do not always coincide with changes in self-reported health. Properties of the HUI scales require further study.

Measuring population health: correlates of the Health Utilities Index among English and French Canadians.

This study used cross-sectional data from the 1994/95 National Population Health Survey (NPHS) in Canada. The objective of the study was to examine the relationship between several established correlates of health status in the general population and the Health Utilities Index (HUI), a multi-dimensional, preference-based measure of health status. Analyses were carried out separately for the English-speaking (n = 9,853) and French-speaking (n = 1,519) respondents. The index correlated strongly with self-ratings of health status and functional disability and varied as expected according to age, sex, and income. Subjects classified to different categories of chronic conditions reported different levels of health, as predicted. The HUI was also associated with the use of drugs and recent history of hospitalization. No major differences in the findings were observed between the two cultural groups. The results should be treated with caution due to the cross-sectional design and other methodological limitations of the study.

The use of the Tobit model for analyzing measures of health status.

Self-reported health status is often measured using psychometric or utility indices that provide a score intended to summarize an individual's health. Measurements of health status can be subject to a ceiling effect. Frequently, researchers want to examine relationships between determinants of health and measures of health status. Regression methods that ignore the presence of a ceiling effect, or of censoring in the health status measurements can produce biased coefficient estimates. The Tobit regression model is a frequently used tool for modeling censored variables in econometrics research. The authors carried out a Monte-Carlo simulation study to contrast the performance of the Tobit model for censored data with that of ordinary least squares (OLS) regression. It was demonstrated that in the presence of a ceiling effect, if the conditional distribution of the measure of health status had uniform variance, then the coefficient estimates from the Tobit model have superior performance compared with estimates from OLS regression. However, if the conditional distribution had non-uniform variance, then the Tobit model performed at least as poorly as the OLS model.

Occupational role performance in persons with back pain.

PURPOSE: Back pain is a major cause of work disability but there is little data on the impact of back pain among persons who are working. The purpose of this study was to develop a measure of occupational role performance for individuals with back pain and to examine its relationship with sociodemographic and work-related factors. METHOD: Item analysis and reduction resulted in a short, eight-item Occupational Role Questionnaire (ORQ) consisting of two scales, a productivity scale and a satisfaction with work scale. The scales had good internal consistency and correlated as expected with the Roland and Morris Disability Scale. RESULTS: In a multivariate logistic model, significant negative effects on work satisfaction were observed for age 30-39 years relative to age 50+, having a job that required lifting, and the level of disability. CONCLUSION: The ORQ may have applications in studying the consequences of back pain and other chronic conditions in the workplace.

The Quebec Back Pain Disability Scale: conceptualization and development.

The Quebec Back Pain Disability Scale is a new measure of functional disability for patients with back pain. Functional disability was operationalized in terms of perceived difficulty associated with simple physical activities. The content of the scale was developed in several stages, including a literature review, two studies seeking the opinions of patients and experts, pilot testing, and a large, longitudinal study of back pain patients. Forty-eight disability items were extensively studied using standard methods such as test-retest reliability, item-total correlations, and factor analysis, as well as modern techniques based on item response theory. Items that were highly effective in discriminating between different levels of disability were selected for the final, reduced scale. The scale has 20 items, representing six empirically derived categories of activities affected by back pain. Measurement properties of this instrument have been previously discussed.

Functional disability scales for back pain.

Functional disability scales for back pain are reviewed for content and measurement properties, concentrating on five widely used questionnaires. Current methodological issues in functional assessment also are discussed.

Concepts of disability: the Activity Space Model.

This paper describes a new conceptual framework for functional assessment, the Activity Space Model (ASM). According to this model, functional impairments may lead to restrictions in an individual's activity space, a multidimensional space that represents human potential for activity. For each elementary ability, restrictions in the corresponding dimension of the activity space can be evaluated by deriving a difficulty curve that depicts the relationship between the level of performance and the psychophysical cost of activity. The effect of disease on daily functioning is explained in terms of a tradeoff between the psychophysical cost and the value of each act of behavior to the disabled individual. These two constructs are measured on the same scale and expressed in units of difficulty. The location of each task within the activity space in relation to the difficulty curve determines whether it will be performed or avoided at a given point in time. The ASM has both theoretical and practical implications. It offers a new, integrated perspective on disability and suggests new strategies for developing and evaluating functional assessment measures.

The Quebec Back Pain Disability Scale. Measurement properties.

STUDY DESIGN: The Quebec Back Pain Disability Scale is a 20-item self-administered instrument designed to assess the level of functional disability in individuals with back pain. The scale was administered as part of a larger questionnaire to a group of 242 back pain patients. Follow-up data were obtained after several days and after 2 to 6 months. OBJECTIVES: The goal of this study was to determine whether the Quebec scale is a reliable, valid, and responsive measure of disability in back pain, and to compare it with other disability scales. SUMMARY OF BACKGROUND DATA: A number of functional disability scales for back pain are being used, but their conceptual validity is uncertain. Unlike most published instruments, the Quebec scale was constructed using a conceptual approach to disability assessment and empirical methods of item development, analysis, and selection. METHODS: The authors calculated test-retest and internal consistency coefficients, evaluated construct validity of the scale, and tested its responsiveness against a global index of change. Direct comparisons with the Roland, Oswestry, and SF-36 scales were carried out. RESULTS: Test-retest reliability was 0.92, and Cronbach's alpha coefficient was 0.96. The scale correlated as expected with other measures of disability, pain, medical history, and utilization variables, work-related variables, and socio-demographic characteristics. Significant changes in disability over time, and differences in change scores between patients that were expected to differ in the direction of change, were found. CONCLUSIONS: The Quebec scale can be recommended as an outcome measure in clinical trials, and for monitoring the progress of individual patients participating in treatment or rehabilitation programs.

Randomized discontinuation trials: utility and efficiency.

The randomized discontinuation trial (RDT) is a two-phase trial. In phase I all patients are openly treated with the medication being evaluated. In phase II, those who have responded are randomly assigned to continue the same treatment or switch to placebo. Usually, non-compliers and "adverse reactors" identified in phase I are excluded from phase II. To investigate the value of this design, we reviewed the advantages and limitations of discontinuation studies, and compared the RDT design to the classic randomized clinical trial design in terms of clinical utility and efficiency (sample size). A computer model was used to study the efficiency of the two designs under a broad range of assumptions. The RDT design is particularly useful in studying the effect of long-term, non-curative therapies, especially when the clinically important effect is relatively small, and the use of placebo should be minimized for ethical or feasibility reasons. However, its use is limited if the objective of an investigation is to estimate the magnitude of absolute treatment effects and toxic effects in the source population, or to evaluate a potentially curative treatment. Our results indicate that selecting responders prior to randomization has a very strong effect on the relative efficiency of the trial. Further improvement may be achieved by excluding non-compliers and adverse reactors. Under the assumptions tested in our model, the sample size required in phase II of an RDT was only 20-50% of that in a classic trial.